diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index f379c103b6940d..6eff6bd7b7c203 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -51,6 +51,7 @@
 #include "llvm/Transforms/Coroutines.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/AlwaysInliner.h"
+#include "llvm/Transforms/IPO/LowerTypeTests.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
 #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
 #include "llvm/Transforms/InstCombine/InstCombine.h"
@@ -553,6 +554,16 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
   std::unique_ptr<TargetLibraryInfoImpl> TLII(
       createTLII(TargetTriple, CodeGenOpts));
 
+  // If we reached here with a non-empty index file name, then the index file
+  // was empty and we are not performing ThinLTO backend compilation (used in
+  // testing in a distributed build environment). Drop any the type test
+  // assume sequences inserted for whole program vtables so that codegen doesn't
+  // complain.
+  if (!CodeGenOpts.ThinLTOIndexFile.empty())
+    MPM.add(createLowerTypeTestsPass(/*ExportSummary=*/nullptr,
+                                     /*ImportSummary=*/nullptr,
+                                     /*DropTypeTests=*/true));
+
   PassManagerBuilderWrapper PMBuilder(TargetTriple, CodeGenOpts, LangOpts);
 
   // At O0 and O1 we only run the always inliner which is more efficient. At
@@ -1114,6 +1125,15 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
     bool IsLTO = CodeGenOpts.PrepareForLTO;
 
     if (CodeGenOpts.OptimizationLevel == 0) {
+      // If we reached here with a non-empty index file name, then the index
+      // file was empty and we are not performing ThinLTO backend compilation
+      // (used in testing in a distributed build environment). Drop any the type
+      // test assume sequences inserted for whole program vtables so that
+      // codegen doesn't complain.
+      if (!CodeGenOpts.ThinLTOIndexFile.empty())
+        MPM.addPass(LowerTypeTestsPass(/*ExportSummary=*/nullptr,
+                                       /*ImportSummary=*/nullptr,
+                                       /*DropTypeTests=*/true));
       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
         MPM.addPass(GCOVProfilerPass(*Options));
       if (Optional<InstrProfOptions> Options =
@@ -1150,6 +1170,18 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
       // configure the pipeline.
       PassBuilder::OptimizationLevel Level = mapToLevel(CodeGenOpts);
 
+      // If we reached here with a non-empty index file name, then the index
+      // file was empty and we are not performing ThinLTO backend compilation
+      // (used in testing in a distributed build environment). Drop any the type
+      // test assume sequences inserted for whole program vtables so that
+      // codegen doesn't complain.
+      if (!CodeGenOpts.ThinLTOIndexFile.empty())
+        PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
+          MPM.addPass(LowerTypeTestsPass(/*ExportSummary=*/nullptr,
+                                         /*ImportSummary=*/nullptr,
+                                         /*DropTypeTests=*/true));
+        });
+
       PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
         MPM.addPass(createModuleToFunctionPassAdaptor(
             EntryExitInstrumenterPass(/*PostInlining=*/false)));
diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 3f3825b7627597..7389207bc8ad19 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -2641,7 +2641,9 @@ void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
   if (SanOpts.has(SanitizerKind::CFIVCall))
     EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
   else if (CGM.getCodeGenOpts().WholeProgramVTables &&
-           CGM.HasHiddenLTOVisibility(RD)) {
+           // Don't insert type test assumes if we are forcing public std
+           // visibility.
+           !CGM.HasLTOVisibilityPublicStd(RD)) {
     llvm::Metadata *MD =
         CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
     llvm::Value *TypeId =
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index cbc969a1ac373c..403b9e25f7a398 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -1011,6 +1011,26 @@ void CodeGenModule::EmitDeferredVTables() {
   DeferredVTables.clear();
 }
 
+bool CodeGenModule::HasLTOVisibilityPublicStd(const CXXRecordDecl *RD) {
+  if (!getCodeGenOpts().LTOVisibilityPublicStd)
+    return false;
+
+  const DeclContext *DC = RD;
+  while (1) {
+    auto *D = cast<Decl>(DC);
+    DC = DC->getParent();
+    if (isa<TranslationUnitDecl>(DC->getRedeclContext())) {
+      if (auto *ND = dyn_cast<NamespaceDecl>(D))
+        if (const IdentifierInfo *II = ND->getIdentifier())
+          if (II->isStr("std") || II->isStr("stdext"))
+            return true;
+      break;
+    }
+  }
+
+  return false;
+}
+
 bool CodeGenModule::HasHiddenLTOVisibility(const CXXRecordDecl *RD) {
   LinkageInfo LV = RD->getLinkageAndVisibility();
   if (!isExternallyVisible(LV.getLinkage()))
@@ -1027,22 +1047,7 @@ bool CodeGenModule::HasHiddenLTOVisibility(const CXXRecordDecl *RD) {
       return false;
   }
 
-  if (getCodeGenOpts().LTOVisibilityPublicStd) {
-    const DeclContext *DC = RD;
-    while (1) {
-      auto *D = cast<Decl>(DC);
-      DC = DC->getParent();
-      if (isa<TranslationUnitDecl>(DC->getRedeclContext())) {
-        if (auto *ND = dyn_cast<NamespaceDecl>(D))
-          if (const IdentifierInfo *II = ND->getIdentifier())
-            if (II->isStr("std") || II->isStr("stdext"))
-              return false;
-        break;
-      }
-    }
-  }
-
-  return true;
+  return !HasLTOVisibilityPublicStd(RD);
 }
 
 llvm::GlobalObject::VCallVisibility
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 115e754bb39200..a711d5ccba0efb 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1292,6 +1292,11 @@ class CodeGenModule : public CodeGenTypeCache {
   /// optimization.
   bool HasHiddenLTOVisibility(const CXXRecordDecl *RD);
 
+  /// Returns whether the given record has public std LTO visibility
+  /// and therefore may not participate in (single-module) CFI and whole-program
+  /// vtable optimization.
+  bool HasLTOVisibilityPublicStd(const CXXRecordDecl *RD);
+
   /// Returns the vcall visibility of the given type. This is the scope in which
   /// a virtual function call could be made which ends up being dispatched to a
   /// member function of this class. This scope can be wider than the visibility
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index b5b8702c551e5f..057c726e355e31 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -670,6 +670,10 @@ CGCallee ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(
                             CGM.HasHiddenLTOVisibility(RD);
   bool ShouldEmitVFEInfo = CGM.getCodeGenOpts().VirtualFunctionElimination &&
                            CGM.HasHiddenLTOVisibility(RD);
+  bool ShouldEmitWPDInfo =
+      CGM.getCodeGenOpts().WholeProgramVTables &&
+      // Don't insert type tests if we are forcing public std visibility.
+      !CGM.HasLTOVisibilityPublicStd(RD);
   llvm::Value *VirtualFn = nullptr;
 
   {
@@ -677,8 +681,9 @@ CGCallee ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(
     llvm::Value *TypeId = nullptr;
     llvm::Value *CheckResult = nullptr;
 
-    if (ShouldEmitCFICheck || ShouldEmitVFEInfo) {
-      // If doing CFI or VFE, we will need the metadata node to check against.
+    if (ShouldEmitCFICheck || ShouldEmitVFEInfo || ShouldEmitWPDInfo) {
+      // If doing CFI, VFE or WPD, we will need the metadata node to check
+      // against.
       llvm::Metadata *MD =
           CGM.CreateMetadataIdentifierForVirtualMemPtrType(QualType(MPT, 0));
       TypeId = llvm::MetadataAsValue::get(CGF.getLLVMContext(), MD);
@@ -702,7 +707,7 @@ CGCallee ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(
     } else {
       // When not doing VFE, emit a normal load, as it allows more
       // optimisations than type.checked.load.
-      if (ShouldEmitCFICheck) {
+      if (ShouldEmitCFICheck || ShouldEmitWPDInfo) {
         CheckResult = Builder.CreateCall(
             CGM.getIntrinsic(llvm::Intrinsic::type_test),
             {Builder.CreateBitCast(VFPAddr, CGF.Int8PtrTy), TypeId});
@@ -713,7 +718,8 @@ CGCallee ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(
                                             "memptr.virtualfn");
     }
     assert(VirtualFn && "Virtual fuction pointer not created!");
-    assert((!ShouldEmitCFICheck || !ShouldEmitVFEInfo || CheckResult) &&
+    assert((!ShouldEmitCFICheck || !ShouldEmitVFEInfo || !ShouldEmitWPDInfo ||
+            CheckResult) &&
            "Check result required but not created!");
 
     if (ShouldEmitCFICheck) {
diff --git a/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll b/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
index 2920cf19c81a94..b46845afba26b9 100644
--- a/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
+++ b/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
@@ -8,6 +8,7 @@
 
 ; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
 ; RUN: llvm-lto2 run -thinlto-distributed-indexes %t.o \
+; RUN:   -whole-program-visibility \
 ; RUN:   -verify-machineinstrs=0 \
 ; RUN:   -o %t2.index \
 ; RUN:   -r=%t.o,test,px \
diff --git a/clang/test/CodeGenCXX/cfi-mfcall.cpp b/clang/test/CodeGenCXX/cfi-mfcall.cpp
index c16b20b8dcec8d..47f3a2616f6050 100644
--- a/clang/test/CodeGenCXX/cfi-mfcall.cpp
+++ b/clang/test/CodeGenCXX/cfi-mfcall.cpp
@@ -1,5 +1,8 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-mfcall -fsanitize-trap=cfi-mfcall -fvisibility hidden -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-mfcall -fsanitize-trap=cfi-mfcall -fvisibility default -emit-llvm -o - %s | FileCheck --check-prefix=DEFAULT %s
+// With -fwhole-program-vtables we should get the member function pointer type
+// test, even without hidden visibility.
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -fwhole-program-vtables -emit-llvm -o - %s | FileCheck %s --check-prefix=WPV
 
 struct B1 {};
 struct B2 {};
@@ -9,6 +12,9 @@ struct S : B1, B3 {};
 // DEFAULT-NOT: llvm.type.test
 
 void f(S *s, void (S::*p)()) {
+  // WPV: [[OFFSET:%.*]] = sub i64 {{.*}}, 1
+  // WPV: [[VFPTR:%.*]] = getelementptr i8, i8* %{{.*}}, i64 [[OFFSET]]
+  // WPV: [[TT:%.*]] = call i1 @llvm.type.test(i8* [[VFPTR]], metadata !"_ZTSM1SFvvE.virtual")
   // CHECK: [[OFFSET:%.*]] = sub i64 {{.*}}, 1
   // CHECK: [[VFPTR:%.*]] = getelementptr i8, i8* %{{.*}}, i64 [[OFFSET]]
   // CHECK: [[TT:%.*]] = call i1 @llvm.type.test(i8* [[VFPTR]], metadata !"_ZTSM1SFvvE.virtual")
diff --git a/clang/test/CodeGenCXX/lto-visibility-inference.cpp b/clang/test/CodeGenCXX/lto-visibility-inference.cpp
index 8e57ef5e0b892e..632b6e643f3018 100644
--- a/clang/test/CodeGenCXX/lto-visibility-inference.cpp
+++ b/clang/test/CodeGenCXX/lto-visibility-inference.cpp
@@ -70,20 +70,20 @@ void f(C1 *c1, C2 *c2, C3 *c3, C4 *c4, C5 *c5, C6 *c6, std::C7 *c7,
   // ITANIUM: type.test{{.*}}!"_ZTS2C1"
   // MS: type.test{{.*}}!"?AUC1@@"
   c1->f();
-  // ITANIUM-NOT: type.test{{.*}}!"_ZTS2C2"
+  // ITANIUM: type.test{{.*}}!"_ZTS2C2"
   // MS: type.test{{.*}}!"?AUC2@@"
   c2->f();
   // ITANIUM: type.test{{.*}}!"_ZTS2C3"
-  // MS-NOT: type.test{{.*}}!"?AUC3@@"
+  // MS: type.test{{.*}}!"?AUC3@@"
   c3->f();
   // ITANIUM: type.test{{.*}}!"_ZTS2C4"
-  // MS-NOT: type.test{{.*}}!"?AUC4@@"
+  // MS: type.test{{.*}}!"?AUC4@@"
   c4->f();
-  // ITANIUM-NOT: type.test{{.*}}!"_ZTS2C5"
-  // MS-NOT: type.test{{.*}}!"?AUC5@@"
+  // ITANIUM: type.test{{.*}}!"_ZTS2C5"
+  // MS: type.test{{.*}}!"?AUC5@@"
   c5->f();
-  // ITANIUM-NOT: type.test{{.*}}!"_ZTS2C6"
-  // MS-NOT: type.test{{.*}}!"?AUC6@@"
+  // ITANIUM: type.test{{.*}}!"_ZTS2C6"
+  // MS: type.test{{.*}}!"?AUC6@@"
   c6->f();
   // ITANIUM: type.test{{.*}}!"_ZTSSt2C7"
   // MS-STD: type.test{{.*}}!"?AUC7@std@@"
diff --git a/clang/test/CodeGenCXX/thinlto-distributed-type-metadata.cpp b/clang/test/CodeGenCXX/thinlto-distributed-type-metadata.cpp
new file mode 100644
index 00000000000000..a6c0da2e4c3caa
--- /dev/null
+++ b/clang/test/CodeGenCXX/thinlto-distributed-type-metadata.cpp
@@ -0,0 +1,69 @@
+// Test distributed ThinLTO backend handling of type tests
+
+// REQUIRES: x86-registered-target
+
+// Ensure that a distributed backend invocation of ThinLTO lowers the type test
+// as expected.
+// RUN: %clang_cc1 -flto=thin -flto-unit -triple x86_64-unknown-linux -fwhole-program-vtables -emit-llvm-bc -o %t.o %s
+// RUN: llvm-dis %t.o -o - | FileCheck --check-prefix=TT %s
+// RUN: llvm-lto -thinlto -o %t2 %t.o
+// RUN: %clang -target x86_64-unknown-linux -O2 -o %t3.o -x ir %t.o -c -fthinlto-index=%t2.thinlto.bc -save-temps=obj
+// RUN: llvm-dis %t.s.4.opt.bc -o - | FileCheck --check-prefix=OPT %s
+// llvm-nm %t3.o | FileCheck --check-prefix=NM %s
+
+// The pre-link bitcode produced by clang should contain a type test assume
+// sequence.
+// TT: [[TTREG:%[0-9]+]] = call i1 @llvm.type.test({{.*}}, metadata !"_ZTS1A")
+// TT: void @llvm.assume(i1 [[TTREG]])
+
+// The ThinLTO backend optimized bitcode should not have any type test assume
+// sequences.
+// OPT-NOT: @llvm.type.test
+// OPT-NOT: call void @llvm.assume
+// We should have only one @llvm.assume call, the one that was expanded
+// from the builtin in the IR below, not the one fed by the type test.
+// OPT: %cmp = icmp ne %struct.A* %{{.*}}, null
+// OPT: void @llvm.assume(i1 %cmp)
+// Check after the builtin assume again that we don't have a type test assume
+// sequence.
+// OPT-NOT: @llvm.type.test
+// OPT-NOT: call void @llvm.assume
+
+// NM: T _Z2afP1A
+
+// Also check type test are lowered when the distributed ThinLTO backend clang
+// invocation is passed an empty index file, in which case a non-ThinLTO
+// compilation pipeline is invoked. If not lowered then LLVM CodeGen may assert.
+// RUN: touch %t4.thinlto.bc
+// O2 old PM
+// RUN: %clang -target x86_64-unknown-linux -O2 -o %t4.o -x ir %t.o -c -fthinlto-index=%t4.thinlto.bc -save-temps=obj
+// RUN: llvm-dis %t.s.4.opt.bc -o - | FileCheck --check-prefix=OPT %s
+// llvm-nm %t4.o | FileCheck --check-prefix=NM %s
+// O2 new PM
+// RUN: %clang -target x86_64-unknown-linux -O2 -o %t4.o -x ir %t.o -c -fthinlto-index=%t4.thinlto.bc -fexperimental-new-pass-manager -save-temps=obj
+// RUN: llvm-dis %t.s.4.opt.bc -o - | FileCheck --check-prefix=OPT %s
+// llvm-nm %t4.o | FileCheck --check-prefix=NM %s
+// O0 new PM
+// RUN: %clang -target x86_64-unknown-linux -O0 -o %t4.o -x ir %t.o -c -fthinlto-index=%t4.thinlto.bc -fexperimental-new-pass-manager -save-temps=obj
+// RUN: llvm-dis %t.s.4.opt.bc -o - | FileCheck --check-prefix=OPT %s
+// llvm-nm %t4.o | FileCheck --check-prefix=NM %s
+
+struct A {
+  A();
+  virtual void f();
+};
+
+struct B : virtual A {
+  B();
+};
+
+A::A() {}
+B::B() {}
+
+void A::f() {
+}
+
+void af(A *a) {
+  __builtin_assume(a != 0);
+  a->f();
+}
diff --git a/clang/test/CodeGenCXX/type-metadata.cpp b/clang/test/CodeGenCXX/type-metadata.cpp
index a7a34673cdfcb5..05731f15b9df5d 100644
--- a/clang/test/CodeGenCXX/type-metadata.cpp
+++ b/clang/test/CodeGenCXX/type-metadata.cpp
@@ -6,6 +6,7 @@
 
 // Tests for the whole-program-vtables feature:
 // RUN: %clang_cc1 -flto -flto-unit -triple x86_64-unknown-linux -fvisibility hidden -fwhole-program-vtables -emit-llvm -o - %s | FileCheck --check-prefix=VTABLE-OPT --check-prefix=ITANIUM --check-prefix=TT-ITANIUM %s
+// RUN: %clang_cc1 -flto -flto-unit -triple x86_64-unknown-linux -fwhole-program-vtables -emit-llvm -o - %s | FileCheck --check-prefix=VTABLE-OPT --check-prefix=ITANIUM-DEFAULTVIS --check-prefix=TT-ITANIUM %s
 // RUN: %clang_cc1 -flto -flto-unit -triple x86_64-pc-windows-msvc -fwhole-program-vtables -emit-llvm -o - %s | FileCheck --check-prefix=VTABLE-OPT --check-prefix=MS --check-prefix=TT-MS %s
 
 // Tests for cfi + whole-program-vtables:
@@ -129,6 +130,7 @@ void D::h() {
 }
 
 // ITANIUM: define hidden void @_Z2afP1A
+// ITANIUM-DEFAULTVIS: define void @_Z2afP1A
 // MS: define dso_local void @"?af@@YAXPEAUA@@@Z"
 void af(A *a) {
   // TT-ITANIUM: [[P:%[^ ]*]] = call i1 @llvm.type.test(i8* [[VT:%[^ ]*]], metadata !"_ZTS1A")
@@ -239,6 +241,7 @@ struct D : C {
 };
 
 // ITANIUM: define hidden void @_ZN5test21fEPNS_1DE
+// ITANIUM-DEFAULTVIS: define void @_ZN5test21fEPNS_1DE
 // MS: define dso_local void @"?f@test2@@YAXPEAUD@1@@Z"
 void f(D *d) {
   // TT-ITANIUM: {{%[^ ]*}} = call i1 @llvm.type.test(i8* {{%[^ ]*}}, metadata !"_ZTSN5test21DE")
diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index ef1edbcd199240..6655ab7a774a52 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -165,6 +165,7 @@ struct Configuration {
   bool ltoCSProfileGenerate;
   bool ltoDebugPassManager;
   bool ltoNewPassManager;
+  bool ltoWholeProgramVisibility;
   bool mergeArmExidx;
   bool mipsN32Abi = false;
   bool mmapOutputFile;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index e85183e14e24f3..eb2fc4f194594c 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -899,6 +899,8 @@ static void readConfigs(opt::InputArgList &args) {
   config->ltoDebugPassManager = args.hasArg(OPT_lto_debug_pass_manager);
   config->ltoNewPassManager = args.hasArg(OPT_lto_new_pass_manager);
   config->ltoNewPmPasses = args.getLastArgValue(OPT_lto_newpm_passes);
+  config->ltoWholeProgramVisibility =
+      args.hasArg(OPT_lto_whole_program_visibility);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
   config->ltoObjPath = args.getLastArgValue(OPT_lto_obj_path_eq);
   config->ltoPartitions = args::getInteger(args, OPT_lto_partitions, 1);
diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
index 2148ac5002916c..d8e343c48871f0 100644
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -111,6 +111,8 @@ static lto::Config createConfig() {
   c.DebugPassManager = config->ltoDebugPassManager;
   c.DwoDir = config->dwoDir;
 
+  c.HasWholeProgramVisibility = config->ltoWholeProgramVisibility;
+
   c.CSIRProfile = config->ltoCSProfileFile;
   c.RunCSIRInstr = config->ltoCSProfileGenerate;
 
diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
index ea78a35262110e..f45ad5a0af28cd 100644
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -479,6 +479,8 @@ def lto_cs_profile_file: J<"lto-cs-profile-file=">,
 def lto_obj_path_eq: J<"lto-obj-path=">;
 def lto_sample_profile: J<"lto-sample-profile=">,
   HelpText<"Sample profile file path">;
+def lto_whole_program_visibility: F<"lto-whole-program-visibility">,
+  HelpText<"Asserts that the LTO link has whole program visibility">;
 def disable_verify: F<"disable-verify">;
 defm mllvm: Eq<"mllvm", "Additional arguments to forward to LLVM's option processing">;
 def opt_remarks_filename: Separate<["--"], "opt-remarks-filename">,
diff --git a/lld/test/ELF/lto/devirt_vcall_vis_public.ll b/lld/test/ELF/lto/devirt_vcall_vis_public.ll
new file mode 100644
index 00000000000000..f07297d5863caf
--- /dev/null
+++ b/lld/test/ELF/lto/devirt_vcall_vis_public.ll
@@ -0,0 +1,128 @@
+; REQUIRES: x86
+; Test that -lto-whole-program-visibility enables devirtualization.
+
+; Index based WPD
+; Generate unsplit module with summary for ThinLTO index-based WPD.
+; RUN: opt -thinlto-bc -o %t2.o %s
+; RUN: ld.lld %t2.o -o %t3 -save-temps -lto-whole-program-visibility \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Hybrid WPD
+; Generate split module with summary for hybrid Thin/Regular LTO WPD.
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t.o %s
+; RUN: ld.lld %t.o -o %t3 -save-temps -lto-whole-program-visibility \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Regular LTO WPD
+; RUN: opt -o %t4.o %s
+; RUN: ld.lld %t4.o -o %t3 -save-temps -lto-whole-program-visibility \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1D1mEi
+
+; Try everything again but without -whole-program-visibility to confirm
+; WPD fails
+
+; Index based WPD
+; RUN: ld.lld %t2.o -o %t3 -save-temps \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+; Hybrid WPD
+; RUN: ld.lld %t.o -o %t3 -save-temps \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+; Regular LTO WPD
+; RUN: ld.lld %t4.o -o %t3 -save-temps \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t3.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+%struct.A = type { i32 (...)** }
+%struct.B = type { %struct.A }
+%struct.C = type { %struct.A }
+%struct.D = type { i32 (...)** }
+
+@_ZTV1B = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !1, !vcall_visibility !5
+@_ZTV1C = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.C*, i32)* @_ZN1C1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !2, !vcall_visibility !5
+@_ZTV1D = constant { [3 x i8*] } { [3 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.D*, i32)* @_ZN1D1mEi to i8*)] }, !type !3, !vcall_visibility !5
+
+
+; CHECK-IR-LABEL: define dso_local i32 @_start
+define i32 @_start(%struct.A* %obj, %struct.D* %obj2, i32 %a) {
+entry:
+  %0 = bitcast %struct.A* %obj to i8***
+  %vtable = load i8**, i8*** %0
+  %1 = bitcast i8** %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
+  call void @llvm.assume(i1 %p)
+  %fptrptr = getelementptr i8*, i8** %vtable, i32 1
+  %2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
+  %fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
+  ; CHECK-NODEVIRT-IR: %call = tail call i32 %fptr1
+  %call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a)
+
+  %3 = bitcast i8** %vtable to i32 (%struct.A*, i32)**
+  %fptr22 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %3, align 8
+
+  ; We still have to call it as virtual.
+  ; CHECK-IR: %call3 = tail call i32 %fptr22
+  ; CHECK-NODEVIRT-IR: %call3 = tail call i32 %fptr22
+  %call3 = tail call i32 %fptr22(%struct.A* nonnull %obj, i32 %call)
+
+  %4 = bitcast %struct.D* %obj2 to i8***
+  %vtable2 = load i8**, i8*** %4
+  %5 = bitcast i8** %vtable2 to i8*
+  %p2 = call i1 @llvm.type.test(i8* %5, metadata !4)
+  call void @llvm.assume(i1 %p2)
+
+  %6 = bitcast i8** %vtable2 to i32 (%struct.D*, i32)**
+  %fptr33 = load i32 (%struct.D*, i32)*, i32 (%struct.D*, i32)** %6, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call4 = tail call i32 @_ZN1D1mEi
+  ; CHECK-NODEVIRT-IR: %call4 = tail call i32 %fptr33
+  %call4 = tail call i32 %fptr33(%struct.D* nonnull %obj2, i32 %call3)
+  ret i32 %call4
+}
+; CHECK-IR-LABEL: ret i32
+; CHECK-IR-LABEL: }
+
+declare i1 @llvm.type.test(i8*, metadata)
+declare void @llvm.assume(i1)
+
+define i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1C1fEi(%struct.C* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1D1mEi(%struct.D* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+; Make sure we don't inline or otherwise optimize out the direct calls.
+attributes #0 = { noinline optnone }
+
+!0 = !{i64 16, !"_ZTS1A"}
+!1 = !{i64 16, !"_ZTS1B"}
+!2 = !{i64 16, !"_ZTS1C"}
+!3 = !{i64 16, !4}
+!4 = distinct !{}
+!5 = !{i64 0}
diff --git a/llvm/include/llvm/LTO/Config.h b/llvm/include/llvm/LTO/Config.h
index 50147300f7f77d..2ca7ad4fda04ab 100644
--- a/llvm/include/llvm/LTO/Config.h
+++ b/llvm/include/llvm/LTO/Config.h
@@ -61,6 +61,10 @@ struct Config {
   /// Run PGO context sensitive IR instrumentation.
   bool RunCSIRInstr = false;
 
+  /// Asserts whether we can assume whole program visibility during the LTO
+  /// link.
+  bool HasWholeProgramVisibility = false;
+
   /// If this field is set, the set of passes run in the middle-end optimizer
   /// will be the one specified by the string. Only works with the new pass
   /// manager as the old one doesn't have this ability.
diff --git a/llvm/include/llvm/Transforms/IPO.h b/llvm/include/llvm/Transforms/IPO.h
index de0c80f5b19acc..daf44822aeb4d7 100644
--- a/llvm/include/llvm/Transforms/IPO.h
+++ b/llvm/include/llvm/Transforms/IPO.h
@@ -236,12 +236,15 @@ enum class PassSummaryAction {
 /// The behavior depends on the summary arguments:
 /// - If ExportSummary is non-null, this pass will export type identifiers to
 ///   the given summary.
-/// - Otherwise, if ImportSummary is non-null, this pass will import type
-///   identifiers from the given summary.
-/// - Otherwise it does neither.
-/// It is invalid for both ExportSummary and ImportSummary to be non-null.
+/// - If ImportSummary is non-null, this pass will import type identifiers from
+///   the given summary.
+/// - Otherwise, if both are null and DropTypeTests is true, all type test
+///   assume sequences will be removed from the IR.
+/// It is invalid for both ExportSummary and ImportSummary to be non-null
+/// unless DropTypeTests is true.
 ModulePass *createLowerTypeTestsPass(ModuleSummaryIndex *ExportSummary,
-                                     const ModuleSummaryIndex *ImportSummary);
+                                     const ModuleSummaryIndex *ImportSummary,
+                                     bool DropTypeTests = false);
 
 /// This pass export CFI checks for use by external modules.
 ModulePass *createCrossDSOCFIPass();
diff --git a/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h b/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h
index 3c2bb65b9552b9..5e91ae599363b8 100644
--- a/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h
+++ b/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h
@@ -201,9 +201,12 @@ class LowerTypeTestsPass : public PassInfoMixin<LowerTypeTestsPass> {
 public:
   ModuleSummaryIndex *ExportSummary;
   const ModuleSummaryIndex *ImportSummary;
+  bool DropTypeTests;
   LowerTypeTestsPass(ModuleSummaryIndex *ExportSummary,
-                     const ModuleSummaryIndex *ImportSummary)
-      : ExportSummary(ExportSummary), ImportSummary(ImportSummary) {}
+                     const ModuleSummaryIndex *ImportSummary,
+                     bool DropTypeTests = false)
+      : ExportSummary(ExportSummary), ImportSummary(ImportSummary),
+        DropTypeTests(DropTypeTests) {}
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
 };
 
diff --git a/llvm/include/llvm/Transforms/IPO/WholeProgramDevirt.h b/llvm/include/llvm/Transforms/IPO/WholeProgramDevirt.h
index 8af2af7f352f4d..86e28cfead80ec 100644
--- a/llvm/include/llvm/Transforms/IPO/WholeProgramDevirt.h
+++ b/llvm/include/llvm/Transforms/IPO/WholeProgramDevirt.h
@@ -236,6 +236,11 @@ struct VTableSlotSummary {
   uint64_t ByteOffset;
 };
 
+void updateVCallVisibilityInModule(Module &M,
+                                   bool WholeProgramVisibilityEnabledInLTO);
+void updateVCallVisibilityInIndex(ModuleSummaryIndex &Index,
+                                  bool WholeProgramVisibilityEnabledInLTO);
+
 /// Perform index-based whole program devirtualization on the \p Summary
 /// index. Any devirtualized targets used by a type test in another module
 /// are added to the \p ExportedGUIDs set. For any local devirtualized targets
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index 297b11de17a90b..e8f0fd6866dc89 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -982,6 +982,11 @@ Error LTO::runRegularLTO(AddStreamFn AddStream) {
     }
   }
 
+  // If allowed, upgrade public vcall visibility metadata to linkage unit
+  // visibility before whole program devirtualization in the optimizer.
+  updateVCallVisibilityInModule(*RegularLTO.CombinedModule,
+                                Conf.HasWholeProgramVisibility);
+
   if (Conf.PreOptModuleHook &&
       !Conf.PreOptModuleHook(0, *RegularLTO.CombinedModule))
     return Error::success();
@@ -1299,6 +1304,11 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
 
   std::set<GlobalValue::GUID> ExportedGUIDs;
 
+  // If allowed, upgrade public vcall visibility to linkage unit visibility in
+  // the summaries before whole program devirtualization below.
+  updateVCallVisibilityInIndex(ThinLTO.CombinedIndex,
+                               Conf.HasWholeProgramVisibility);
+
   // Perform index-based WPD. This will return immediately if there are
   // no index entries in the typeIdMetadata map (e.g. if we are instead
   // performing IR-based WPD in hybrid regular/thin LTO mode).
diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index 5fef14230a9bb2..b3bc727e50adcb 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -57,6 +57,7 @@
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/Internalize.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
+#include "llvm/Transforms/IPO/WholeProgramDevirt.h"
 #include "llvm/Transforms/ObjCARC.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 #include <system_error>
@@ -542,6 +543,13 @@ bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
   }
   StatsFile = std::move(StatsFileOrErr.get());
 
+  // Currently there is no support for enabling whole program visibility via a
+  // linker option in the old LTO API, but this call allows it to be specified
+  // via the internal option. Must be done before WPD invoked via the optimizer
+  // pipeline run below.
+  updateVCallVisibilityInModule(*MergedModule,
+                                /* WholeProgramVisibilityEnabledInLTO */ false);
+
   // We always run the verifier once on the merged module, the `DisableVerify`
   // parameter only applies to subsequent verify.
   verifyMergedModuleOnce();
diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index 0bb518bf6cceb5..f4099e68315ee4 100644
--- a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -969,6 +969,12 @@ void ThinLTOCodeGenerator::run() {
   // Synthesize entry counts for functions in the combined index.
   computeSyntheticCounts(*Index);
 
+  // Currently there is no support for enabling whole program visibility via a
+  // linker option in the old LTO API, but this call allows it to be specified
+  // via the internal option. Must be done before WPD below.
+  updateVCallVisibilityInIndex(*Index,
+                               /* WholeProgramVisibilityEnabledInLTO */ false);
+
   // Perform index-based WPD. This will return immediately if there are
   // no index entries in the typeIdMetadata map (e.g. if we are instead
   // performing IR-based WPD in hybrid regular/thin LTO mode).
diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
index e6747a68e67265..6eba35aaa4ed70 100644
--- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -382,6 +382,9 @@ class LowerTypeTestsModule {
 
   ModuleSummaryIndex *ExportSummary;
   const ModuleSummaryIndex *ImportSummary;
+  // Set when the client has invoked this to simply drop all type test assume
+  // sequences.
+  bool DropTypeTests;
 
   Triple::ArchType Arch;
   Triple::OSType OS;
@@ -500,7 +503,8 @@ class LowerTypeTestsModule {
 
 public:
   LowerTypeTestsModule(Module &M, ModuleSummaryIndex *ExportSummary,
-                       const ModuleSummaryIndex *ImportSummary);
+                       const ModuleSummaryIndex *ImportSummary,
+                       bool DropTypeTests);
 
   bool lower();
 
@@ -516,22 +520,24 @@ struct LowerTypeTests : public ModulePass {
 
   ModuleSummaryIndex *ExportSummary;
   const ModuleSummaryIndex *ImportSummary;
+  bool DropTypeTests;
 
   LowerTypeTests() : ModulePass(ID), UseCommandLine(true) {
     initializeLowerTypeTestsPass(*PassRegistry::getPassRegistry());
   }
 
   LowerTypeTests(ModuleSummaryIndex *ExportSummary,
-                 const ModuleSummaryIndex *ImportSummary)
+                 const ModuleSummaryIndex *ImportSummary, bool DropTypeTests)
       : ModulePass(ID), ExportSummary(ExportSummary),
-        ImportSummary(ImportSummary) {
+        ImportSummary(ImportSummary), DropTypeTests(DropTypeTests) {
     initializeLowerTypeTestsPass(*PassRegistry::getPassRegistry());
   }
 
   bool runOnModule(Module &M) override {
     if (UseCommandLine)
       return LowerTypeTestsModule::runForTesting(M);
-    return LowerTypeTestsModule(M, ExportSummary, ImportSummary).lower();
+    return LowerTypeTestsModule(M, ExportSummary, ImportSummary, DropTypeTests)
+        .lower();
   }
 };
 
@@ -544,8 +550,9 @@ INITIALIZE_PASS(LowerTypeTests, "lowertypetests", "Lower type metadata", false,
 
 ModulePass *
 llvm::createLowerTypeTestsPass(ModuleSummaryIndex *ExportSummary,
-                               const ModuleSummaryIndex *ImportSummary) {
-  return new LowerTypeTests(ExportSummary, ImportSummary);
+                               const ModuleSummaryIndex *ImportSummary,
+                               bool DropTypeTests) {
+  return new LowerTypeTests(ExportSummary, ImportSummary, DropTypeTests);
 }
 
 /// Build a bit set for TypeId using the object layouts in
@@ -1655,8 +1662,9 @@ void LowerTypeTestsModule::buildBitSetsFromDisjointSet(
 /// Lower all type tests in this module.
 LowerTypeTestsModule::LowerTypeTestsModule(
     Module &M, ModuleSummaryIndex *ExportSummary,
-    const ModuleSummaryIndex *ImportSummary)
-    : M(M), ExportSummary(ExportSummary), ImportSummary(ImportSummary) {
+    const ModuleSummaryIndex *ImportSummary, bool DropTypeTests)
+    : M(M), ExportSummary(ExportSummary), ImportSummary(ImportSummary),
+      DropTypeTests(DropTypeTests) {
   assert(!(ExportSummary && ImportSummary));
   Triple TargetTriple(M.getTargetTriple());
   Arch = TargetTriple.getArch();
@@ -1683,7 +1691,8 @@ bool LowerTypeTestsModule::runForTesting(Module &M) {
   bool Changed =
       LowerTypeTestsModule(
           M, ClSummaryAction == PassSummaryAction::Export ? &Summary : nullptr,
-          ClSummaryAction == PassSummaryAction::Import ? &Summary : nullptr)
+          ClSummaryAction == PassSummaryAction::Import ? &Summary : nullptr,
+          /*DropTypeTests*/ false)
           .lower();
 
   if (!ClWriteSummary.empty()) {
@@ -1750,6 +1759,33 @@ void LowerTypeTestsModule::replaceDirectCalls(Value *Old, Value *New) {
 }
 
 bool LowerTypeTestsModule::lower() {
+  Function *TypeTestFunc =
+      M.getFunction(Intrinsic::getName(Intrinsic::type_test));
+
+  if (DropTypeTests && TypeTestFunc) {
+    for (auto UI = TypeTestFunc->use_begin(), UE = TypeTestFunc->use_end();
+         UI != UE;) {
+      auto *CI = cast<CallInst>((*UI++).getUser());
+      // Find and erase llvm.assume intrinsics for this llvm.type.test call.
+      for (auto CIU = CI->use_begin(), CIUE = CI->use_end(); CIU != CIUE;) {
+        if (auto *AssumeCI = dyn_cast<CallInst>((*CIU++).getUser())) {
+          Function *F = AssumeCI->getCalledFunction();
+          if (F && F->getIntrinsicID() == Intrinsic::assume)
+            AssumeCI->eraseFromParent();
+        }
+      }
+      CI->eraseFromParent();
+    }
+
+    // We have deleted the type intrinsics, so we no longer have enough
+    // information to reason about the liveness of virtual function pointers
+    // in GlobalDCE.
+    for (GlobalVariable &GV : M.globals())
+      GV.eraseMetadata(LLVMContext::MD_vcall_visibility);
+
+    return true;
+  }
+
   // If only some of the modules were split, we cannot correctly perform
   // this transformation. We already checked for the presense of type tests
   // with partially split modules during the thin link, and would have emitted
@@ -1758,8 +1794,6 @@ bool LowerTypeTestsModule::lower() {
       (ImportSummary && ImportSummary->partiallySplitLTOUnits()))
     return false;
 
-  Function *TypeTestFunc =
-      M.getFunction(Intrinsic::getName(Intrinsic::type_test));
   Function *ICallBranchFunnelFunc =
       M.getFunction(Intrinsic::getName(Intrinsic::icall_branch_funnel));
   if ((!TypeTestFunc || TypeTestFunc->use_empty()) &&
@@ -2196,7 +2230,9 @@ bool LowerTypeTestsModule::lower() {
 
 PreservedAnalyses LowerTypeTestsPass::run(Module &M,
                                           ModuleAnalysisManager &AM) {
-  bool Changed = LowerTypeTestsModule(M, ExportSummary, ImportSummary).lower();
+  bool Changed =
+      LowerTypeTestsModule(M, ExportSummary, ImportSummary, DropTypeTests)
+          .lower();
   if (!Changed)
     return PreservedAnalyses::all();
   return PreservedAnalyses::none();
diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
index 58cd99abcb5f00..5c5ddf4a38c839 100644
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -140,6 +140,22 @@ static cl::opt<bool>
                        cl::init(false), cl::ZeroOrMore,
                        cl::desc("Print index-based devirtualization messages"));
 
+/// Provide a way to force enable whole program visibility in tests.
+/// This is needed to support legacy tests that don't contain
+/// !vcall_visibility metadata (the mere presense of type tests
+/// previously implied hidden visibility).
+cl::opt<bool>
+    WholeProgramVisibility("whole-program-visibility", cl::init(false),
+                           cl::Hidden, cl::ZeroOrMore,
+                           cl::desc("Enable whole program visibility"));
+
+/// Provide a way to force disable whole program for debugging or workarounds,
+/// when enabled via the linker.
+cl::opt<bool> DisableWholeProgramVisibility(
+    "disable-whole-program-visibility", cl::init(false), cl::Hidden,
+    cl::ZeroOrMore,
+    cl::desc("Disable whole program visibility (overrides enabling options)"));
+
 // Find the minimum offset that we may store a value of size Size bits at. If
 // IsAfter is set, look for an offset before the object, otherwise look for an
 // offset after the object.
@@ -708,7 +724,49 @@ PreservedAnalyses WholeProgramDevirtPass::run(Module &M,
   return PreservedAnalyses::none();
 }
 
+// Enable whole program visibility if enabled by client (e.g. linker) or
+// internal option, and not force disabled.
+static bool hasWholeProgramVisibility(bool WholeProgramVisibilityEnabledInLTO) {
+  return (WholeProgramVisibilityEnabledInLTO || WholeProgramVisibility) &&
+         !DisableWholeProgramVisibility;
+}
+
 namespace llvm {
+
+/// If whole program visibility asserted, then upgrade all public vcall
+/// visibility metadata on vtable definitions to linkage unit visibility in
+/// Module IR (for regular or hybrid LTO).
+void updateVCallVisibilityInModule(Module &M,
+                                   bool WholeProgramVisibilityEnabledInLTO) {
+  if (!hasWholeProgramVisibility(WholeProgramVisibilityEnabledInLTO))
+    return;
+  for (GlobalVariable &GV : M.globals())
+    // Add linkage unit visibility to any variable with type metadata, which are
+    // the vtable definitions. We won't have an existing vcall_visibility
+    // metadata on vtable definitions with public visibility.
+    if (GV.hasMetadata(LLVMContext::MD_type) &&
+        GV.getVCallVisibility() == GlobalObject::VCallVisibilityPublic)
+      GV.setVCallVisibilityMetadata(GlobalObject::VCallVisibilityLinkageUnit);
+}
+
+/// If whole program visibility asserted, then upgrade all public vcall
+/// visibility metadata on vtable definition summaries to linkage unit
+/// visibility in Module summary index (for ThinLTO).
+void updateVCallVisibilityInIndex(ModuleSummaryIndex &Index,
+                                  bool WholeProgramVisibilityEnabledInLTO) {
+  if (!hasWholeProgramVisibility(WholeProgramVisibilityEnabledInLTO))
+    return;
+  for (auto &P : Index) {
+    for (auto &S : P.second.SummaryList) {
+      auto *GVar = dyn_cast<GlobalVarSummary>(S.get());
+      if (!GVar || GVar->vTableFuncs().empty() ||
+          GVar->getVCallVisibility() != GlobalObject::VCallVisibilityPublic)
+        continue;
+      GVar->setVCallVisibility(GlobalObject::VCallVisibilityLinkageUnit);
+    }
+  }
+}
+
 void runWholeProgramDevirtOnIndex(
     ModuleSummaryIndex &Summary, std::set<GlobalValue::GUID> &ExportedGUIDs,
     std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
@@ -853,6 +911,12 @@ bool DevirtModule::tryFindVirtualCallTargets(
     if (!TM.Bits->GV->isConstant())
       return false;
 
+    // We cannot perform whole program devirtualization analysis on a vtable
+    // with public LTO visibility.
+    if (TM.Bits->GV->getVCallVisibility() ==
+        GlobalObject::VCallVisibilityPublic)
+      return false;
+
     Constant *Ptr = getPointerAtOffset(TM.Bits->GV->getInitializer(),
                                        TM.Offset + ByteOffset, M);
     if (!Ptr)
@@ -898,8 +962,13 @@ bool DevirtIndex::tryFindVirtualCallTargets(
           return false;
         LocalFound = true;
       }
-      if (!GlobalValue::isAvailableExternallyLinkage(S->linkage()))
+      if (!GlobalValue::isAvailableExternallyLinkage(S->linkage())) {
         VS = cast<GlobalVarSummary>(S->getBaseObject());
+        // We cannot perform whole program devirtualization analysis on a vtable
+        // with public LTO visibility.
+        if (VS->getVCallVisibility() == GlobalObject::VCallVisibilityPublic)
+          return false;
+      }
     }
     if (!VS->isLive())
       continue;
@@ -1843,6 +1912,12 @@ bool DevirtModule::run() {
 
     removeRedundantTypeTests();
 
+    // We have lowered or deleted the type instrinsics, so we will no
+    // longer have enough information to reason about the liveness of virtual
+    // function pointers in GlobalDCE.
+    for (GlobalVariable &GV : M.globals())
+      GV.eraseMetadata(LLVMContext::MD_vcall_visibility);
+
     // The rest of the code is only necessary when exporting or during regular
     // LTO, so we are done.
     return true;
@@ -1966,7 +2041,7 @@ bool DevirtModule::run() {
     for (VTableBits &B : Bits)
       rebuildGlobal(B);
 
-  // We have lowered or deleted the type checked load intrinsics, so we no
+  // We have lowered or deleted the type instrinsics, so we will no
   // longer have enough information to reason about the liveness of virtual
   // function pointers in GlobalDCE.
   for (GlobalVariable &GV : M.globals())
diff --git a/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll b/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll
index 6618a6f280fe62..b52cceeb52cd2a 100644
--- a/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll
+++ b/llvm/test/ThinLTO/X86/cache-typeid-resolutions.ll
@@ -9,17 +9,17 @@
 ; where both t and t-import are sensitive to typeid1's resolution
 ; so 4 distinct objects in total.
 ; RUN: rm -rf %t.cache
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f1_actual,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t1.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f1_actual,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -r=%t1.bc,vt1,plx
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f1_actual,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -whole-program-visibility
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t1.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f1_actual,plx -r=%t.bc,f2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -r=%t1.bc,vt1,plx -whole-program-visibility
 ; RUN: ls %t.cache | count 4
 
 ; Three resolutions for typeid2: Indir, SingleImpl, UniqueRetVal
 ; where both t and t-import are sensitive to typeid2's resolution
 ; so 6 distinct objects in total.
 ; RUN: rm -rf %t.cache
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t2.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t2.bc,vt2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
-; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t3.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t3.bc,vt2a,plx -r=%t3.bc,vt2b,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -whole-program-visibility
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t2.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t2.bc,vt2,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -whole-program-visibility
+; RUN: llvm-lto2 run -o %t.o %t.bc %t-import.bc %t3.bc -cache-dir %t.cache -r=%t.bc,f1,plx -r=%t.bc,f2,plx -r=%t.bc,f1_actual,plx -r=%t3.bc,vt2a,plx -r=%t3.bc,vt2b,plx -r=%t-import.bc,importf1,plx -r=%t-import.bc,f1,lx -r=%t-import.bc,importf2,plx -r=%t-import.bc,f2,lx -whole-program-visibility
 ; RUN: ls %t.cache | count 6
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/ThinLTO/X86/cfi-devirt.ll b/llvm/test/ThinLTO/X86/cfi-devirt.ll
index dd83024e263443..311bed084deebf 100644
--- a/llvm/test/ThinLTO/X86/cfi-devirt.ll
+++ b/llvm/test/ThinLTO/X86/cfi-devirt.ll
@@ -6,6 +6,7 @@
 
 ; Legacy PM
 ; RUN: llvm-lto2 run %t.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,test,px \
 ; RUN:   -r=%t.o,_ZN1A1nEi,p \
@@ -23,6 +24,7 @@
 
 ; New PM
 ; RUN: llvm-lto2 run %t.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,test,px \
 ; RUN:   -r=%t.o,_ZN1A1nEi,p \
@@ -46,6 +48,7 @@
 ; to ensure it is being caught in the thin link.
 ; RUN: opt -thinlto-bc -o %t2.o %S/Inputs/empty.ll
 ; RUN: not llvm-lto2 run %t.o %t2.o -thinlto-distributed-indexes \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,test,px \
 ; RUN:   -r=%t.o,_ZN1A1nEi,p \
diff --git a/llvm/test/ThinLTO/X86/devirt-after-icp.ll b/llvm/test/ThinLTO/X86/devirt-after-icp.ll
index af6eba77ba4e72..e4ac5549867e70 100644
--- a/llvm/test/ThinLTO/X86/devirt-after-icp.ll
+++ b/llvm/test/ThinLTO/X86/devirt-after-icp.ll
@@ -46,6 +46,7 @@
 
 ; Legacy PM
 ; RUN: llvm-lto2 run %t.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,_Z3bazP1A,px \
 ; RUN:   -r=%t.o,_ZN1A3fooEv, \
@@ -64,6 +65,7 @@
 
 ; New PM
 ; RUN: llvm-lto2 run %t.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,_Z3bazP1A,px \
 ; RUN:   -r=%t.o,_ZN1A3fooEv, \
diff --git a/llvm/test/ThinLTO/X86/devirt.ll b/llvm/test/ThinLTO/X86/devirt.ll
index eae8c69eb06135..c24685c5d6bf4e 100644
--- a/llvm/test/ThinLTO/X86/devirt.ll
+++ b/llvm/test/ThinLTO/X86/devirt.ll
@@ -35,6 +35,7 @@
 
 ; Legacy PM, Index based WPD
 ; RUN: llvm-lto2 run %t2.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t2.o,test,px \
 ; RUN:   -r=%t2.o,_ZN1A1nEi,p \
@@ -48,6 +49,7 @@
 
 ; New PM, Index based WPD
 ; RUN: llvm-lto2 run %t2.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t2.o,test,px \
 ; RUN:   -r=%t2.o,_ZN1A1nEi,p \
@@ -62,6 +64,7 @@
 ; Legacy PM
 ; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
 ; RUN: llvm-lto2 run %t.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -verify-machineinstrs=0 \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,test,px \
@@ -84,6 +87,7 @@
 ; New PM
 ; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
 ; RUN: llvm-lto2 run %t.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -verify-machineinstrs=0 \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,test,px \
diff --git a/llvm/test/ThinLTO/X86/devirt2.ll b/llvm/test/ThinLTO/X86/devirt2.ll
index 01eed382f24c91..a2cffa7be8c3e9 100644
--- a/llvm/test/ThinLTO/X86/devirt2.ll
+++ b/llvm/test/ThinLTO/X86/devirt2.ll
@@ -36,6 +36,7 @@
 
 ; Legacy PM, Index based WPD
 ; RUN: llvm-lto2 run %t3.o %t4.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -wholeprogramdevirt-print-index-based \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t3.o,test,px \
@@ -59,6 +60,7 @@
 
 ; New PM, Index based WPD
 ; RUN: llvm-lto2 run %t3.o %t4.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -wholeprogramdevirt-print-index-based \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t3.o,test,px \
@@ -92,6 +94,7 @@
 
 ; Index based WPD, distributed backends
 ; RUN: llvm-lto2 run %t3.o %t4.o -save-temps -use-new-pm \
+; RUN:   -whole-program-visibility \
 ; RUN:   -thinlto-distributed-indexes -wholeprogramdevirt-print-index-based \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t3.o,test,px \
@@ -115,6 +118,7 @@
 
 ; Legacy PM
 ; RUN: llvm-lto2 run %t1.o %t2.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t1.o,test,px \
 ; RUN:   -r=%t1.o,_ZTV1B, \
@@ -150,6 +154,7 @@
 
 ; New PM
 ; RUN: llvm-lto2 run %t1.o %t2.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t1.o,test,px \
 ; RUN:   -r=%t1.o,_ZTV1B, \
diff --git a/llvm/test/ThinLTO/X86/devirt_alias.ll b/llvm/test/ThinLTO/X86/devirt_alias.ll
index 92aa2bcba917f0..78ebd471b010c3 100644
--- a/llvm/test/ThinLTO/X86/devirt_alias.ll
+++ b/llvm/test/ThinLTO/X86/devirt_alias.ll
@@ -7,6 +7,7 @@
 ; RUN: opt -thinlto-bc -o %t4.o %p/Inputs/devirt_alias.ll
 
 ; RUN: llvm-lto2 run %t3.o %t4.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -wholeprogramdevirt-print-index-based \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t3.o,test,px \
diff --git a/llvm/test/ThinLTO/X86/devirt_available_externally.ll b/llvm/test/ThinLTO/X86/devirt_available_externally.ll
index 128055f7022ec5..94ab7b75758748 100644
--- a/llvm/test/ThinLTO/X86/devirt_available_externally.ll
+++ b/llvm/test/ThinLTO/X86/devirt_available_externally.ll
@@ -18,6 +18,7 @@
 ; EXTERNAL: gv: (name: "_ZTV1D", {{.*}} vTableFuncs: ((virtFunc:
 
 ; RUN: llvm-lto2 run %t3.o %t4.o -save-temps -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -wholeprogramdevirt-print-index-based \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t3.o,test,px \
diff --git a/llvm/test/ThinLTO/X86/devirt_external_comdat_same_guid.ll b/llvm/test/ThinLTO/X86/devirt_external_comdat_same_guid.ll
index 18482a051e2f3b..ce2f9b7175d6d2 100644
--- a/llvm/test/ThinLTO/X86/devirt_external_comdat_same_guid.ll
+++ b/llvm/test/ThinLTO/X86/devirt_external_comdat_same_guid.ll
@@ -8,6 +8,7 @@
 ; RUN: opt -thinlto-bc -o %t4.o %p/Inputs/devirt_external_comdat_same_guid.ll
 
 ; RUN: llvm-lto2 run %t3.o %t4.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -wholeprogramdevirt-print-index-based \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t3.o,use_B,px \
diff --git a/llvm/test/ThinLTO/X86/devirt_promote.ll b/llvm/test/ThinLTO/X86/devirt_promote.ll
index 563ed994157a29..e93b4192cf1804 100644
--- a/llvm/test/ThinLTO/X86/devirt_promote.ll
+++ b/llvm/test/ThinLTO/X86/devirt_promote.ll
@@ -10,6 +10,7 @@
 ; RUN: opt -thinlto-bc -o %t4.o %p/Inputs/devirt_promote.ll
 
 ; RUN: llvm-lto2 run %t3.o %t4.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
 ; RUN:   -wholeprogramdevirt-print-index-based \
 ; RUN:   -o %t5 \
 ; RUN:   -r=%t3.o,test,px \
diff --git a/llvm/test/ThinLTO/X86/devirt_promote_legacy.ll b/llvm/test/ThinLTO/X86/devirt_promote_legacy.ll
index 79fde540c5971d..7216911a6bc664 100644
--- a/llvm/test/ThinLTO/X86/devirt_promote_legacy.ll
+++ b/llvm/test/ThinLTO/X86/devirt_promote_legacy.ll
@@ -10,6 +10,7 @@
 ; RUN: opt -thinlto-bc -o %t4.o %p/Inputs/devirt_promote.ll
 
 ; RUN: llvm-lto -thinlto-action=run %t3.o %t4.o --thinlto-save-temps=%t5. \
+; RUN:   -whole-program-visibility \
 ; RUN:   --pass-remarks=. \
 ; RUN:   --exported-symbol=test \
 ; RUN:   --exported-symbol=test2 \
diff --git a/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll b/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll
index 5b2df6cf6f9be6..5966794152c167 100644
--- a/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll
+++ b/llvm/test/ThinLTO/X86/devirt_single_hybrid.ll
@@ -5,6 +5,7 @@
 ; RUN: opt -thinlto-bc -thinlto-split-lto-unit %p/Inputs/devirt_single_hybrid_foo.ll -o %t-foo.bc
 ; RUN: opt -thinlto-bc -thinlto-split-lto-unit %p/Inputs/devirt_single_hybrid_bar.ll -o %t-bar.bc
 ; RUN: llvm-lto2 run -save-temps %t-main.bc %t-foo.bc %t-bar.bc -pass-remarks=. -o %t \
+; RUN:   -whole-program-visibility \
 ; RUN:    -r=%t-foo.bc,_Z3fooP1A,pl \
 ; RUN:    -r=%t-main.bc,main,plx \
 ; RUN:    -r=%t-main.bc,_Z3barv,l \
diff --git a/llvm/test/ThinLTO/X86/devirt_vcall_vis_hidden.ll b/llvm/test/ThinLTO/X86/devirt_vcall_vis_hidden.ll
new file mode 100644
index 00000000000000..7a301491e05d13
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/devirt_vcall_vis_hidden.ll
@@ -0,0 +1,143 @@
+; REQUIRES: x86-registered-target
+
+; Test devirtualization through the thin link and backend, when vtables
+; have vcall_visibility metadata with public visibility.
+
+; Index based WPD
+; Generate unsplit module with summary for ThinLTO index-based WPD.
+; RUN: opt -thinlto-bc -o %t2.o %s
+; RUN: llvm-lto2 run %t2.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -o %t3 \
+; RUN:   -r=%t2.o,test,px \
+; RUN:   -r=%t2.o,_ZN1A1nEi,p \
+; RUN:   -r=%t2.o,_ZN1B1fEi,p \
+; RUN:   -r=%t2.o,_ZN1C1fEi,p \
+; RUN:   -r=%t2.o,_ZN1D1mEi,p \
+; RUN:   -r=%t2.o,_ZTV1B,px \
+; RUN:   -r=%t2.o,_ZTV1C,px \
+; RUN:   -r=%t2.o,_ZTV1D,px 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Hybrid WPD
+; Generate split module with summary for hybrid Thin/Regular LTO WPD.
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t.o %s
+; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
+; RUN: llvm-lto2 run %t.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -verify-machineinstrs=0 \
+; RUN:   -o %t3 \
+; RUN:   -r=%t.o,test,px \
+; RUN:   -r=%t.o,_ZN1A1nEi,p \
+; RUN:   -r=%t.o,_ZN1B1fEi,p \
+; RUN:   -r=%t.o,_ZN1C1fEi,p \
+; RUN:   -r=%t.o,_ZN1D1mEi,p \
+; RUN:   -r=%t.o,_ZTV1B, \
+; RUN:   -r=%t.o,_ZTV1C, \
+; RUN:   -r=%t.o,_ZTV1D, \
+; RUN:   -r=%t.o,_ZN1A1nEi, \
+; RUN:   -r=%t.o,_ZN1B1fEi, \
+; RUN:   -r=%t.o,_ZN1C1fEi, \
+; RUN:   -r=%t.o,_ZN1D1mEi, \
+; RUN:   -r=%t.o,_ZTV1B,px \
+; RUN:   -r=%t.o,_ZTV1C,px \
+; RUN:   -r=%t.o,_ZTV1D,px 2>&1 | FileCheck %s --check-prefix=REMARK --dump-input=fail
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Regular LTO WPD
+; RUN: opt -o %t4.o %s
+; RUN: llvm-lto2 run %t4.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -o %t5 \
+; RUN:   -r=%t4.o,test,px \
+; RUN:   -r=%t4.o,_ZN1A1nEi,p \
+; RUN:   -r=%t4.o,_ZN1B1fEi,p \
+; RUN:   -r=%t4.o,_ZN1C1fEi,p \
+; RUN:   -r=%t4.o,_ZN1D1mEi,p \
+; RUN:   -r=%t4.o,_ZTV1B,px \
+; RUN:   -r=%t4.o,_ZTV1C,px \
+; RUN:   -r=%t4.o,_ZTV1D,px 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t5.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1D1mEi
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+%struct.A = type { i32 (...)** }
+%struct.B = type { %struct.A }
+%struct.C = type { %struct.A }
+%struct.D = type { i32 (...)** }
+
+@_ZTV1B = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !1, !vcall_visibility !5
+@_ZTV1C = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.C*, i32)* @_ZN1C1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !2, !vcall_visibility !5
+@_ZTV1D = constant { [3 x i8*] } { [3 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.D*, i32)* @_ZN1D1mEi to i8*)] }, !type !3, !vcall_visibility !5
+
+
+; CHECK-IR-LABEL: define i32 @test
+define i32 @test(%struct.A* %obj, %struct.D* %obj2, i32 %a) {
+entry:
+  %0 = bitcast %struct.A* %obj to i8***
+  %vtable = load i8**, i8*** %0
+  %1 = bitcast i8** %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
+  call void @llvm.assume(i1 %p)
+  %fptrptr = getelementptr i8*, i8** %vtable, i32 1
+  %2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
+  %fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
+  %call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a)
+
+  %3 = bitcast i8** %vtable to i32 (%struct.A*, i32)**
+  %fptr22 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %3, align 8
+
+  ; We still have to call it as virtual.
+  ; CHECK-IR: %call3 = tail call i32 %fptr22
+  %call3 = tail call i32 %fptr22(%struct.A* nonnull %obj, i32 %call)
+
+  %4 = bitcast %struct.D* %obj2 to i8***
+  %vtable2 = load i8**, i8*** %4
+  %5 = bitcast i8** %vtable2 to i8*
+  %p2 = call i1 @llvm.type.test(i8* %5, metadata !4)
+  call void @llvm.assume(i1 %p2)
+
+  %6 = bitcast i8** %vtable2 to i32 (%struct.D*, i32)**
+  %fptr33 = load i32 (%struct.D*, i32)*, i32 (%struct.D*, i32)** %6, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call4 = tail call i32 @_ZN1D1mEi
+  %call4 = tail call i32 %fptr33(%struct.D* nonnull %obj2, i32 %call3)
+  ret i32 %call4
+}
+; CHECK-IR-LABEL: ret i32
+; CHECK-IR-LABEL: }
+
+declare i1 @llvm.type.test(i8*, metadata)
+declare void @llvm.assume(i1)
+
+define i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1C1fEi(%struct.C* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1D1mEi(%struct.D* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+; Make sure we don't inline or otherwise optimize out the direct calls.
+attributes #0 = { noinline optnone }
+
+!0 = !{i64 16, !"_ZTS1A"}
+!1 = !{i64 16, !"_ZTS1B"}
+!2 = !{i64 16, !"_ZTS1C"}
+!3 = !{i64 16, !4}
+!4 = distinct !{}
+!5 = !{i64 1}
diff --git a/llvm/test/ThinLTO/X86/devirt_vcall_vis_public.ll b/llvm/test/ThinLTO/X86/devirt_vcall_vis_public.ll
new file mode 100644
index 00000000000000..468237bea4c805
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/devirt_vcall_vis_public.ll
@@ -0,0 +1,215 @@
+; REQUIRES: x86-registered-target
+
+; Test devirtualization through the thin link and backend, when vtables
+; have vcall_visibility metadata with public visibility.
+
+; Index based WPD
+; Generate unsplit module with summary for ThinLTO index-based WPD.
+; RUN: opt -thinlto-bc -o %t2.o %s
+; RUN: llvm-lto2 run %t2.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -o %t3 \
+; RUN:   -r=%t2.o,test,px \
+; RUN:   -r=%t2.o,_ZN1A1nEi,p \
+; RUN:   -r=%t2.o,_ZN1B1fEi,p \
+; RUN:   -r=%t2.o,_ZN1C1fEi,p \
+; RUN:   -r=%t2.o,_ZN1D1mEi,p \
+; RUN:   -r=%t2.o,_ZTV1B,px \
+; RUN:   -r=%t2.o,_ZTV1C,px \
+; RUN:   -r=%t2.o,_ZTV1D,px 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Hybrid WPD
+; Generate split module with summary for hybrid Thin/Regular LTO WPD.
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t.o %s
+; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
+; RUN: llvm-lto2 run %t.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -verify-machineinstrs=0 \
+; RUN:   -o %t3 \
+; RUN:   -r=%t.o,test,px \
+; RUN:   -r=%t.o,_ZN1A1nEi,p \
+; RUN:   -r=%t.o,_ZN1B1fEi,p \
+; RUN:   -r=%t.o,_ZN1C1fEi,p \
+; RUN:   -r=%t.o,_ZN1D1mEi,p \
+; RUN:   -r=%t.o,_ZTV1B, \
+; RUN:   -r=%t.o,_ZTV1C, \
+; RUN:   -r=%t.o,_ZTV1D, \
+; RUN:   -r=%t.o,_ZN1A1nEi, \
+; RUN:   -r=%t.o,_ZN1B1fEi, \
+; RUN:   -r=%t.o,_ZN1C1fEi, \
+; RUN:   -r=%t.o,_ZN1D1mEi, \
+; RUN:   -r=%t.o,_ZTV1B,px \
+; RUN:   -r=%t.o,_ZTV1C,px \
+; RUN:   -r=%t.o,_ZTV1D,px 2>&1 | FileCheck %s --check-prefix=REMARK --dump-input=fail
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Regular LTO WPD
+; RUN: opt -o %t4.o %s
+; RUN: llvm-lto2 run %t4.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -o %t5 \
+; RUN:   -r=%t4.o,test,px \
+; RUN:   -r=%t4.o,_ZN1A1nEi,p \
+; RUN:   -r=%t4.o,_ZN1B1fEi,p \
+; RUN:   -r=%t4.o,_ZN1C1fEi,p \
+; RUN:   -r=%t4.o,_ZN1D1mEi,p \
+; RUN:   -r=%t4.o,_ZTV1B,px \
+; RUN:   -r=%t4.o,_ZTV1C,px \
+; RUN:   -r=%t4.o,_ZTV1D,px 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t5.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1D1mEi
+
+; Try everything again but without -whole-program-visibility to confirm
+; WPD fails
+
+; Index based WPD
+; RUN: llvm-lto2 run %t2.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -o %t3 \
+; RUN:   -r=%t2.o,test,px \
+; RUN:   -r=%t2.o,_ZN1A1nEi,p \
+; RUN:   -r=%t2.o,_ZN1B1fEi,p \
+; RUN:   -r=%t2.o,_ZN1C1fEi,p \
+; RUN:   -r=%t2.o,_ZN1D1mEi,p \
+; RUN:   -r=%t2.o,_ZTV1B,px \
+; RUN:   -r=%t2.o,_ZTV1C,px \
+; RUN:   -r=%t2.o,_ZTV1D,px 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+; Hybrid WPD
+; RUN: llvm-lto2 run %t.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -verify-machineinstrs=0 \
+; RUN:   -o %t3 \
+; RUN:   -r=%t.o,test,px \
+; RUN:   -r=%t.o,_ZN1A1nEi,p \
+; RUN:   -r=%t.o,_ZN1B1fEi,p \
+; RUN:   -r=%t.o,_ZN1C1fEi,p \
+; RUN:   -r=%t.o,_ZN1D1mEi,p \
+; RUN:   -r=%t.o,_ZTV1B, \
+; RUN:   -r=%t.o,_ZTV1C, \
+; RUN:   -r=%t.o,_ZTV1D, \
+; RUN:   -r=%t.o,_ZN1A1nEi, \
+; RUN:   -r=%t.o,_ZN1B1fEi, \
+; RUN:   -r=%t.o,_ZN1C1fEi, \
+; RUN:   -r=%t.o,_ZN1D1mEi, \
+; RUN:   -r=%t.o,_ZTV1B,px \
+; RUN:   -r=%t.o,_ZTV1C,px \
+; RUN:   -r=%t.o,_ZTV1D,px 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+; Regular LTO WPD
+; RUN: llvm-lto2 run %t4.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -o %t5 \
+; RUN:   -r=%t4.o,test,px \
+; RUN:   -r=%t4.o,_ZN1A1nEi,p \
+; RUN:   -r=%t4.o,_ZN1B1fEi,p \
+; RUN:   -r=%t4.o,_ZN1C1fEi,p \
+; RUN:   -r=%t4.o,_ZN1D1mEi,p \
+; RUN:   -r=%t4.o,_ZTV1B,px \
+; RUN:   -r=%t4.o,_ZTV1C,px \
+; RUN:   -r=%t4.o,_ZTV1D,px 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t5.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+; Try index-based WPD again with both -whole-program-visibility and
+; -disable-whole-program-visibility to confirm the latter overrides
+; the former and that WPD fails.
+; RUN: llvm-lto2 run %t2.o -save-temps -use-new-pm -pass-remarks=. \
+; RUN:   -whole-program-visibility \
+; RUN:   -disable-whole-program-visibility \
+; RUN:   -o %t3 \
+; RUN:   -r=%t2.o,test,px \
+; RUN:   -r=%t2.o,_ZN1A1nEi,p \
+; RUN:   -r=%t2.o,_ZN1B1fEi,p \
+; RUN:   -r=%t2.o,_ZN1C1fEi,p \
+; RUN:   -r=%t2.o,_ZN1D1mEi,p \
+; RUN:   -r=%t2.o,_ZTV1B,px \
+; RUN:   -r=%t2.o,_ZTV1C,px \
+; RUN:   -r=%t2.o,_ZTV1D,px 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+%struct.A = type { i32 (...)** }
+%struct.B = type { %struct.A }
+%struct.C = type { %struct.A }
+%struct.D = type { i32 (...)** }
+
+@_ZTV1B = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !1, !vcall_visibility !5
+@_ZTV1C = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.C*, i32)* @_ZN1C1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !2, !vcall_visibility !5
+@_ZTV1D = constant { [3 x i8*] } { [3 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.D*, i32)* @_ZN1D1mEi to i8*)] }, !type !3, !vcall_visibility !5
+
+
+; CHECK-IR-LABEL: define i32 @test
+define i32 @test(%struct.A* %obj, %struct.D* %obj2, i32 %a) {
+entry:
+  %0 = bitcast %struct.A* %obj to i8***
+  %vtable = load i8**, i8*** %0
+  %1 = bitcast i8** %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
+  call void @llvm.assume(i1 %p)
+  %fptrptr = getelementptr i8*, i8** %vtable, i32 1
+  %2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
+  %fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
+  ; CHECK-NODEVIRT-IR: %call = tail call i32 %fptr1
+  %call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a)
+
+  %3 = bitcast i8** %vtable to i32 (%struct.A*, i32)**
+  %fptr22 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %3, align 8
+
+  ; We still have to call it as virtual.
+  ; CHECK-IR: %call3 = tail call i32 %fptr22
+  ; CHECK-NODEVIRT-IR: %call3 = tail call i32 %fptr22
+  %call3 = tail call i32 %fptr22(%struct.A* nonnull %obj, i32 %call)
+
+  %4 = bitcast %struct.D* %obj2 to i8***
+  %vtable2 = load i8**, i8*** %4
+  %5 = bitcast i8** %vtable2 to i8*
+  %p2 = call i1 @llvm.type.test(i8* %5, metadata !4)
+  call void @llvm.assume(i1 %p2)
+
+  %6 = bitcast i8** %vtable2 to i32 (%struct.D*, i32)**
+  %fptr33 = load i32 (%struct.D*, i32)*, i32 (%struct.D*, i32)** %6, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call4 = tail call i32 @_ZN1D1mEi
+  ; CHECK-NODEVIRT-IR: %call4 = tail call i32 %fptr33
+  %call4 = tail call i32 %fptr33(%struct.D* nonnull %obj2, i32 %call3)
+  ret i32 %call4
+}
+; CHECK-IR-LABEL: ret i32
+; CHECK-IR-LABEL: }
+
+declare i1 @llvm.type.test(i8*, metadata)
+declare void @llvm.assume(i1)
+
+define i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1C1fEi(%struct.C* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1D1mEi(%struct.D* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+; Make sure we don't inline or otherwise optimize out the direct calls.
+attributes #0 = { noinline optnone }
+
+!0 = !{i64 16, !"_ZTS1A"}
+!1 = !{i64 16, !"_ZTS1B"}
+!2 = !{i64 16, !"_ZTS1C"}
+!3 = !{i64 16, !4}
+!4 = distinct !{}
+!5 = !{i64 0}
diff --git a/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll
index e5d0e74b22e2d8..14de02a23c0649 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/bad-read-from-vtable.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/branch-funnel-threshold.ll b/llvm/test/Transforms/WholeProgramDevirt/branch-funnel-threshold.ll
index 91cd4e419b661f..1e7d38d9bdbfd7 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/branch-funnel-threshold.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/branch-funnel-threshold.ll
@@ -1,8 +1,8 @@
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -wholeprogramdevirt-branch-funnel-threshold=1 -S -o - %s | not grep @llvm.icall.branch.funnel | count 0
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -wholeprogramdevirt-branch-funnel-threshold=1 -S -o - %s | not grep @llvm.icall.branch.funnel | count 0
 
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -wholeprogramdevirt-branch-funnel-threshold=10 -S -o - %s | grep @llvm.icall.branch.funnel | count 4
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -wholeprogramdevirt-branch-funnel-threshold=10 -S -o - %s | grep @llvm.icall.branch.funnel | count 4
 
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -wholeprogramdevirt-branch-funnel-threshold=100 -S -o - %s | grep @llvm.icall.branch.funnel | count 5
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -wholeprogramdevirt-branch-funnel-threshold=100 -S -o - %s | grep @llvm.icall.branch.funnel | count 5
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/branch-funnel.ll b/llvm/test/Transforms/WholeProgramDevirt/branch-funnel.ll
index db76080725bcde..32d964819fee5c 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/branch-funnel.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/branch-funnel.ll
@@ -1,9 +1,9 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck --check-prefixes=CHECK,RETP %s
-; RUN: sed -e 's,+retpoline,-retpoline,g' %s | opt -S -wholeprogramdevirt | FileCheck --check-prefixes=CHECK,NORETP %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck --check-prefixes=CHECK,RETP %s
+; RUN: sed -e 's,+retpoline,-retpoline,g' %s | opt -S -wholeprogramdevirt -whole-program-visibility | FileCheck --check-prefixes=CHECK,NORETP %s
 
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck --check-prefixes=CHECK,RETP %s
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck --check-prefixes=CHECK,RETP %s
 
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t  -O3 -S -o - %s | FileCheck --check-prefixes=CHECK %s
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t  -O3 -S -o - %s | FileCheck --check-prefixes=CHECK %s
 
 ; RUN: FileCheck --check-prefix=SUMMARY %s < %t
 
diff --git a/llvm/test/Transforms/WholeProgramDevirt/constant-arg.ll b/llvm/test/Transforms/WholeProgramDevirt/constant-arg.ll
index f65e4132738203..2f26a2502e9c0b 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/constant-arg.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/constant-arg.ll
@@ -1,5 +1,5 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
-; RUN: opt -S -passes=wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
+; RUN: opt -S -passes=wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll
index f4ef8824e2e8b5..7302238aa7cdca 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl-check.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll
index 9f631e94cf545e..5b0b5aabdae49b 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl2.ll b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl2.ll
index 4c45c4081df10b..63ccfb833d4560 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl2.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/devirt-single-impl2.ll
@@ -2,7 +2,7 @@
 ; loading/saving index from/to bitcode
 ; RUN: llvm-as %s -o %t.bc
 ; RUN: llvm-as %p/Inputs/devirt-single-impl2-index.ll -o %t.index.bc
-; RUN: opt %s -S -wholeprogramdevirt -wholeprogramdevirt-read-summary=%t.index.bc \
+; RUN: opt %s -S -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-read-summary=%t.index.bc \
 ; RUN:     -wholeprogramdevirt-summary-action=export \
 ; RUN:     -wholeprogramdevirt-write-summary=%t2.index.bc -o /dev/null
 ; RUN: llvm-dis %t2.index.bc -o - | FileCheck %s
@@ -10,7 +10,7 @@
 ; Check that opt fails to use summaries which don't contain regular LTO module
 ; when performing export.
 ; RUN: llvm-as %p/Inputs/devirt-bad-index.ll -o %t-bad.index.bc
-; RUN: not opt %s -S -wholeprogramdevirt -wholeprogramdevirt-read-summary=%t-bad.index.bc \
+; RUN: not opt %s -S -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-read-summary=%t-bad.index.bc \
 ; RUN:     -wholeprogramdevirt-summary-action=export -o /dev/null 2>&1 | FileCheck %s --check-prefix=MISSING-MODULE
 
 ; Check single impl devirtulation in summary
diff --git a/llvm/test/Transforms/WholeProgramDevirt/expand-check.ll b/llvm/test/Transforms/WholeProgramDevirt/expand-check.ll
index 4effaba08b25b9..3ea078a183e862 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/expand-check.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/expand-check.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 ; Test that we correctly expand the llvm.type.checked.load intrinsic in cases
 ; where we cannot devirtualize.
diff --git a/llvm/test/Transforms/WholeProgramDevirt/export-nothing.ll b/llvm/test/Transforms/WholeProgramDevirt/export-nothing.ll
index 4707eaa17ead34..64a714dd08d665 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/export-nothing.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/export-nothing.ll
@@ -1,4 +1,4 @@
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-write-summary=%t -o /dev/null %s
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-write-summary=%t -o /dev/null %s
 ; RUN: FileCheck %s < %t
 
 ; CHECK: ---
diff --git a/llvm/test/Transforms/WholeProgramDevirt/export-single-impl.ll b/llvm/test/Transforms/WholeProgramDevirt/export-single-impl.ll
index cbba1a4d1644cc..33ff9e1afe50f6 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/export-single-impl.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/export-single-impl.ll
@@ -1,4 +1,4 @@
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck %s
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck %s
 ; RUN: FileCheck --check-prefix=SUMMARY %s < %t
 
 ; SUMMARY:      TypeIdMap:
diff --git a/llvm/test/Transforms/WholeProgramDevirt/export-uniform-ret-val.ll b/llvm/test/Transforms/WholeProgramDevirt/export-uniform-ret-val.ll
index 43adb90d69f1c2..cb2fddd75d1d0e 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/export-uniform-ret-val.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/export-uniform-ret-val.ll
@@ -1,4 +1,4 @@
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck %s
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck %s
 ; RUN: FileCheck --check-prefix=SUMMARY %s < %t
 
 ; SUMMARY-NOT: TypeTests:
diff --git a/llvm/test/Transforms/WholeProgramDevirt/export-unique-ret-val.ll b/llvm/test/Transforms/WholeProgramDevirt/export-unique-ret-val.ll
index 4260a2e570d16a..0f780a3873687c 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/export-unique-ret-val.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/export-unique-ret-val.ll
@@ -1,4 +1,4 @@
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck %s
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck %s
 ; RUN: FileCheck --check-prefix=SUMMARY %s < %t
 
 ; SUMMARY-NOT:  TypeTests:
diff --git a/llvm/test/Transforms/WholeProgramDevirt/export-unsuccessful-checked.ll b/llvm/test/Transforms/WholeProgramDevirt/export-unsuccessful-checked.ll
index 3132444a9f36aa..dd16fa052afc43 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/export-unsuccessful-checked.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/export-unsuccessful-checked.ll
@@ -1,4 +1,4 @@
-; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -o /dev/null %s
+; RUN: opt -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -o /dev/null %s
 ; RUN: FileCheck %s < %t
 
 ; CHECK:       TypeTests: [ 15427464259790519041, 17525413373118030901 ]
diff --git a/llvm/test/Transforms/WholeProgramDevirt/export-vcp.ll b/llvm/test/Transforms/WholeProgramDevirt/export-vcp.ll
index 5982ad4ec58f1d..eb7b36e87dd62b 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/export-vcp.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/export-vcp.ll
@@ -1,7 +1,7 @@
-; RUN: opt -mtriple=x86_64-unknown-linux-gnu -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck --check-prefixes=CHECK,X86 %s
+; RUN: opt -mtriple=x86_64-unknown-linux-gnu -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck --check-prefixes=CHECK,X86 %s
 ; RUN: FileCheck --check-prefixes=SUMMARY,SUMMARY-X86 %s < %t
 
-; RUN: opt -mtriple=armv7-unknown-linux-gnu -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck --check-prefixes=CHECK,ARM %s
+; RUN: opt -mtriple=armv7-unknown-linux-gnu -wholeprogramdevirt -whole-program-visibility -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck --check-prefixes=CHECK,ARM %s
 ; RUN: FileCheck --check-prefixes=SUMMARY,SUMMARY-ARM %s < %t
 
 target datalayout = "e-p:64:64"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
index ecc8ad0e7c73e2..1a38efa01ec9ee 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/non-constant-vtable.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
 
 ; CHECK-NOT: devirtualized call
 
diff --git a/llvm/test/Transforms/WholeProgramDevirt/pointer-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/pointer-vtable.ll
index 5e76a5a7dde476..443a850373d1d8 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/pointer-vtable.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/pointer-vtable.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll
index 3b6afc52e5dc89..86c9a9938512cd 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/soa-vtable.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/struct-vtable.ll b/llvm/test/Transforms/WholeProgramDevirt/struct-vtable.ll
index 81e41d466941be..8afa1d99c508a6 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/struct-vtable.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/struct-vtable.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll b/llvm/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll
index 8fea9bc7b24002..b9d205939364a9 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/uniform-retval-invoke.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/uniform-retval.ll b/llvm/test/Transforms/WholeProgramDevirt/uniform-retval.ll
index ef3a7e49b52c2b..7626aba24c1ab5 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/uniform-retval.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/uniform-retval.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/unique-retval.ll b/llvm/test/Transforms/WholeProgramDevirt/unique-retval.ll
index 4452bb75d03f8e..f03c07d24de653 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/unique-retval.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/unique-retval.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll b/llvm/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll
index ca76383c49434c..07a9ac7e2300ac 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vcp-accesses-memory.ll
@@ -1,5 +1,5 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
-; RUN: opt -S -passes=wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
+; RUN: opt -S -passes=wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vcp-decl.ll b/llvm/test/Transforms/WholeProgramDevirt/vcp-decl.ll
index 1c4e2fbe97aa4c..35be7e4cabd336 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vcp-decl.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vcp-decl.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vcp-no-this.ll b/llvm/test/Transforms/WholeProgramDevirt/vcp-no-this.ll
index ce76c8e6797e38..0c3c4e9b2ff53a 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vcp-no-this.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vcp-no-this.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll b/llvm/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll
index cc2ff33296a998..3580663b7f06e0 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vcp-non-constant-arg.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll b/llvm/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll
index c24c3b4be68323..a0de6d278331bb 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vcp-too-wide-ints.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll b/llvm/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll
index 7016263f8f7ba2..e96323e3d782d9 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vcp-type-mismatch.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 ; Test that we correctly handle function type mismatches in argument counts
 ; and bitwidths. We handle an argument count mismatch by refusing
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll b/llvm/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll
index 542402e1657727..1c5b0ae05b18f2 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vcp-uses-this.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll
index 6e55235ebfcd82..22426dfc4497e6 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll
index 3299f7bce65bca..b7537f26e4d054 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-check.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility -pass-remarks=wholeprogramdevirt %s 2>&1 | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll
index 5ab9571a0caadf..b3cb4de7240ead 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/WholeProgramDevirt/vtable-decl.ll b/llvm/test/Transforms/WholeProgramDevirt/vtable-decl.ll
index e56170a4997f2c..cdb3856c70f85a 100644
--- a/llvm/test/Transforms/WholeProgramDevirt/vtable-decl.ll
+++ b/llvm/test/Transforms/WholeProgramDevirt/vtable-decl.ll
@@ -1,5 +1,5 @@
 ; Check that we don't crash when processing declaration with type metadata
-; RUN: opt -S -wholeprogramdevirt %s
+; RUN: opt -S -wholeprogramdevirt -whole-program-visibility %s
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-none-linux-gnu"
diff --git a/llvm/test/tools/gold/X86/devirt_vcall_vis_public.ll b/llvm/test/tools/gold/X86/devirt_vcall_vis_public.ll
new file mode 100644
index 00000000000000..53cd3fd4e361aa
--- /dev/null
+++ b/llvm/test/tools/gold/X86/devirt_vcall_vis_public.ll
@@ -0,0 +1,148 @@
+; Test that plugin option whole-program-visibility enables devirtualization.
+
+; Index based WPD
+; Generate unsplit module with summary for ThinLTO index-based WPD.
+; RUN: opt -thinlto-bc -o %t2.o %s
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:   --plugin-opt=whole-program-visibility \
+; RUN:   --plugin-opt=save-temps \
+; RUN:   --plugin-opt=-pass-remarks=. \
+; RUN:   %t2.o -o %t3 \
+; RUN: 	 --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Hybrid WPD
+; Generate split module with summary for hybrid Thin/Regular LTO WPD.
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t.o %s
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:   --plugin-opt=whole-program-visibility \
+; RUN:   --plugin-opt=save-temps \
+; RUN:   --plugin-opt=-pass-remarks=. \
+; RUN:   %t.o -o %t3 \
+; RUN: 	 --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; Regular LTO WPD
+; RUN: opt -o %t4.o %s
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:   --plugin-opt=whole-program-visibility \
+; RUN:   --plugin-opt=save-temps \
+; RUN:   --plugin-opt=-pass-remarks=. \
+; RUN:   %t4.o -o %t3 \
+; RUN: 	 --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
+; REMARK-DAG: single-impl: devirtualized a call to _ZN1D1mEi
+
+; Try everything again but without -whole-program-visibility to confirm
+; WPD fails
+
+; Index based WPD
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:   --plugin-opt=save-temps \
+; RUN:   --plugin-opt=-pass-remarks=. \
+; RUN:   %t2.o -o %t3 \
+; RUN: 	 --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+; Hybrid WPD
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:   --plugin-opt=save-temps \
+; RUN:   --plugin-opt=-pass-remarks=. \
+; RUN:   %t.o -o %t3 \
+; RUN: 	 --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+; Regular LTO WPD
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:   --plugin-opt=save-temps \
+; RUN:   --plugin-opt=-pass-remarks=. \
+; RUN:   %t4.o -o %t3 \
+; RUN: 	 --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t3.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+%struct.A = type { i32 (...)** }
+%struct.B = type { %struct.A }
+%struct.C = type { %struct.A }
+%struct.D = type { i32 (...)** }
+
+@_ZTV1B = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !1, !vcall_visibility !5
+@_ZTV1C = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.C*, i32)* @_ZN1C1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !2, !vcall_visibility !5
+@_ZTV1D = constant { [3 x i8*] } { [3 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.D*, i32)* @_ZN1D1mEi to i8*)] }, !type !3, !vcall_visibility !5
+
+
+; CHECK-IR-LABEL: define dso_local i32 @_start
+define i32 @_start(%struct.A* %obj, %struct.D* %obj2, i32 %a) {
+entry:
+  %0 = bitcast %struct.A* %obj to i8***
+  %vtable = load i8**, i8*** %0
+  %1 = bitcast i8** %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
+  call void @llvm.assume(i1 %p)
+  %fptrptr = getelementptr i8*, i8** %vtable, i32 1
+  %2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
+  %fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
+  ; CHECK-NODEVIRT-IR: %call = tail call i32 %fptr1
+  %call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a)
+
+  %3 = bitcast i8** %vtable to i32 (%struct.A*, i32)**
+  %fptr22 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %3, align 8
+
+  ; We still have to call it as virtual.
+  ; CHECK-IR: %call3 = tail call i32 %fptr22
+  ; CHECK-NODEVIRT-IR: %call3 = tail call i32 %fptr22
+  %call3 = tail call i32 %fptr22(%struct.A* nonnull %obj, i32 %call)
+
+  %4 = bitcast %struct.D* %obj2 to i8***
+  %vtable2 = load i8**, i8*** %4
+  %5 = bitcast i8** %vtable2 to i8*
+  %p2 = call i1 @llvm.type.test(i8* %5, metadata !4)
+  call void @llvm.assume(i1 %p2)
+
+  %6 = bitcast i8** %vtable2 to i32 (%struct.D*, i32)**
+  %fptr33 = load i32 (%struct.D*, i32)*, i32 (%struct.D*, i32)** %6, align 8
+
+  ; Check that the call was devirtualized.
+  ; CHECK-IR: %call4 = tail call i32 @_ZN1D1mEi
+  ; CHECK-NODEVIRT-IR: %call4 = tail call i32 %fptr33
+  %call4 = tail call i32 %fptr33(%struct.D* nonnull %obj2, i32 %call3)
+  ret i32 %call4
+}
+; CHECK-IR-LABEL: ret i32
+; CHECK-IR-LABEL: }
+
+declare i1 @llvm.type.test(i8*, metadata)
+declare void @llvm.assume(i1)
+
+define i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1C1fEi(%struct.C* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+define i32 @_ZN1D1mEi(%struct.D* %this, i32 %a) #0 {
+   ret i32 0;
+}
+
+; Make sure we don't inline or otherwise optimize out the direct calls.
+attributes #0 = { noinline optnone }
+
+!0 = !{i64 16, !"_ZTS1A"}
+!1 = !{i64 16, !"_ZTS1B"}
+!2 = !{i64 16, !"_ZTS1C"}
+!3 = !{i64 16, !4}
+!4 = distinct !{}
+!5 = !{i64 0}
diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
index 406079dad307e9..93e9b60873ebf6 100644
--- a/llvm/tools/gold/gold-plugin.cpp
+++ b/llvm/tools/gold/gold-plugin.cpp
@@ -204,6 +204,8 @@ namespace options {
   static std::string dwo_dir;
   /// Statistics output filename.
   static std::string stats_file;
+  // Asserts that LTO link has whole program visibility
+  static bool whole_program_visibility = false;
 
   // Optimization remarks filename, accepted passes and hotness options
   static std::string RemarksFilename;
@@ -283,6 +285,8 @@ namespace options {
       new_pass_manager = true;
     } else if (opt == "debug-pass-manager") {
       debug_pass_manager = true;
+    } else if (opt == "whole-program-visibility") {
+      whole_program_visibility = true;
     } else if (opt.startswith("dwo_dir=")) {
       dwo_dir = opt.substr(strlen("dwo_dir="));
     } else if (opt.startswith("opt-remarks-filename=")) {
@@ -926,6 +930,8 @@ static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
   // Debug new pass manager if requested
   Conf.DebugPassManager = options::debug_pass_manager;
 
+  Conf.HasWholeProgramVisibility = options::whole_program_visibility;
+
   Conf.StatsFile = options::stats_file;
   return std::make_unique<LTO>(std::move(Conf), Backend,
                                 options::ParallelCodeGenParallelismLevel);
diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index 75a6cdc3892b33..82cf47d9ebd605 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -54,6 +54,7 @@
 #include "llvm/Transforms/Coroutines.h"
 #include "llvm/Transforms/IPO/AlwaysInliner.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
+#include "llvm/Transforms/IPO/WholeProgramDevirt.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 #include "llvm/Transforms/Utils/Debugify.h"
 #include <algorithm>
@@ -625,6 +626,13 @@ int main(int argc, char **argv) {
     return 1;
   }
 
+  // Enable testing of whole program devirtualization on this module by invoking
+  // the facility for updating public visibility to linkage unit visibility when
+  // specified by an internal option. This is normally done during LTO which is
+  // not performed via opt.
+  updateVCallVisibilityInModule(*M,
+                                /* WholeProgramVisibilityEnabledInLTO */ false);
+
   // Figure out what stream we are supposed to write to...
   std::unique_ptr<ToolOutputFile> Out;
   std::unique_ptr<ToolOutputFile> ThinLinkOut;